The present invention relates to a defect inspection method for inspecting an infinitesimal defect existing on the surface of a sample, identifying the type and dimensions of the defect, and outputting the result, and relates to a defect inspection device provided for the method.
In order to sustain and/or improve the yield of a product on a manufacturing line of a semiconductor substrate, the semiconductor substrate and the thin-film substrate or the like is inspected for a defect existing on the surface. Known documents describing conventional defect-inspection technologies include Japanese Patent Application Laid-Open No. Hei9-304289 (used as PTL 1), Japanese Patent Application Laid-Open No. 2006-201179 (used as PTL 2) and US Patent Application Ser. No. 2006/0256325 (used as PTL 3). In accordance with these technologies, in order to detect an infinitesimal defect existing on the surface of a sample, illumination light is converged to dimensions of several tens of microns and radiated to the surface. Then, scattered light from the defect is surface. Then, scattered light from the defect is converged and detected to inspect the surface for the defect having dimensions ranging from several tens of nanometers to at least several tens of microns. A stage for holding the sample (the object of inspection) is moved in a rotation and a parallel movement to scan the surface of the sample by making use of an illumination-light spot moving along a spiral-like path. In this way, the entire surface of the sample is inspected.
In addition, in accordance with the technologies described in PTLs 1 and 2, components of the scattered light from a defect are detected. To be more specific, the components are emitted in a large-angle direction and a small-angle direction. Then, the component ratio is used for identifying the type of the defect.
In addition, in accordance with the technology described in PTL 2, the dimensions of a detected defect are computed on the basis of the strength of scattered light from the defect.
In addition, in accordance with the technology described in PTL 3, in order to reduce a thermal damage incurred by the sample, while the object of inspection is being inspected, the power of the illumination light, the scanning velocity of the illumination-light spot or the dimensions of the illumination-light spot are controlled. To put it concretely, the thermal damage incurred by the sample is assumed to have a magnitude determined by the product of the illumination power density of the radiated light and the radiation time. Then, the power of the illumination light, the scanning velocity of the illumination-light spot or the dimensions of the illumination-light spot are changed in accordance with radial position of the illumination spot on the sample being scanned so that the magnitude of the thermal damage does not exceed a fixed value.